We propose to investigate the functional significance of gene order in the chromosome of the bacterium Salmonella typhyimurium. We will select a vareity of chromosomal rearrangements and will look for evidence that particular rearrangements have lethal or deleterious consequences for cell function. Studes will include the effect of chromosme position on gene expression and on localization of gene products. We will determine whether gene position affects time of gene expression in the cell cycle. By recombinant DNA techniques the joint points of rearrangements will be cloned and analyzed to determine whether homologous sequences were involved in the exchange and if IS sequences catalyzed the event. The mechanism of chromosome rearrangement by Tn5 will be studied including identification of genes required for Tn5-mediated exchanges and determination of whether these functions are regulated.